This invention relates to a colour photographic material having at least one spectrally sensitised silver halide emulsion layer, which contains an oil former, together with a coupler which releases a development inhibitor on colour development.
It is known t o perform chromogenic development in the presence of compounds which, on development, release diffusible substances in accordance with the image, which substances perform a certain action, for example are capable of influencing silver halide development. In the event that said action comprises inhibition of further development, such compounds are known as DIR (=Development Inhibitor Releasing) compounds. DIR compounds may comprise those which react with a colour developer oxidation product with elimination of an inhibitor residue to yield a dye (DIR couplers) or those which release the inhibitor without simultaneously forming a dye. The latter are also strictly speaking known as DIR compounds.
DIR couplers are frequently introduced into photographic layers as emulsions. Emulsions are finely divided dispersions of oil in an aqueous medium, wherein the oil droplets then consist of a solution of DIR couplers in a high-boiling solvent, the xe2x80x9coil formerxe2x80x9d. Conventional oil formers, such as for example tricresyl phosphate, which is very frequently used, are hydrophobic. EP 536 889 does, however, also disclose the use of DIR couplers together with special protic oil formers in green-sensitive silver halide emulsion layers containing pyrazoloazole magenta couplers. According to said application, the special oil formers make it possible to offset the disadvantages of pyrazoloazole magenta couplers, such as poor processing stability.
DIR couplers give rise to a desired increase in the interimage effect in colour photographic materials. DIR couplers may also improve sharpness and grain. However, as a result of development inhibition, the use of DIR couplers also results in an unwanted reduction in sensitivity.
The object underlying the invention is to provide a colour photographic material which contains at least one DIR coupler together with at least one oil former and in which the interimage effect is increased in comparison with the prior art, but in which the use of the DIR coupler brings about no reduction in sensitivity in comparison with the prior art.
The present invention provides a colour photographic recording material having at least one spectrally sensitised silver halide emulsion layer, characterised in that said silver halide emulsion layer contains an oil former having a pKa value of less than 18 and a DIR coupler and the material contains at least one colour coupler which complies with the formulae 
in which
R1, R6, R9 mean alkyl aryl;
R2 means chlorine, alkoxy;
R3 means acyl, acylamino;
R4, R5, R8 mean alkyl;
R7 means aryl;
L1 means a single bond, xe2x80x94COxe2x80x94;
Y1, means hydrogen, carbamoyloxy;
X1 means hydrogen, chlorine;
Z1 means a heterocyclic, nitrogenous, N-linked 5-membered ring;
Z2 means hydrogen, alkylsulfido, arylsulfido or a heteroaromatic, nitrogenous, N-linked, 5-membered ring;
Z3 means hydrogen, chlorine, alkoxy, aryloxy, alkylsulfido and
p means 1 or 2,
and wherein R4 and R5 may form a 5- or 6-membered ring.
The pK3 values of the oil formers are determined by titration with tetrabutyl-ammonium hydroxide (TBAH) in dimethyl sulfoxide/water (100:0.25), as described in xe2x80x9cAcid Base Titrations in Nonaqueous Solventsxe2x80x9d, Allyn and Bacon Inc., Boston 1973 and in W. Huber xe2x80x9cTitration in nichtwxc3xa4ssrigen Lxc3x6sungsmittelnxe2x80x9d, Akademische Verlagsgesellschaft, Frankfurt am Main 1964.
It has surprisingly been found that an increased interimage effect is achieved with the embodiment of the photographic material according to the invention, without any reduction in sensitivity.
Compounds (K-1) to (K-20) are examples of suitable couplers of the formulae (K-I), (K-II), (K-III), (K-IV) and (K-V). 
Particularly preferred colour couplers are of the formula (K-III).
Suitable DIR couplers for the purposes of the present invention may be found in Research Disclosure 37254, part 5 (1995), page 290, in Research Disclosure 37038, part XIV (1995), page 86 and in Research Disclosure 38957, part X c (1996), page 618.
In a preferred embodiment, the DIR coupler complies with the formula (D-I), 
wherein
Q1 means the remaining members to complete a fused and optionally substituted benzene or heteroaromatic ring;
X1 means O or NR2;
R1 means alkyl, aryl, hetaryl or alkenyl;
R2 means H or R1;
INH means 
Time means a linking member which, on reaction of the coupler with the oxidation product of a silver halide developer, is released together with the residue INH attached thereto and in turn releases the residue INH with a delay under development conditions;
R11, R12 mean H, alkyl, aryl, alkaryl, xe2x80x94Sxe2x80x94R13, xe2x80x94COOxe2x80x94R13, xe2x80x94CON(R13)R14, xe2x80x94N(R15)R16, xe2x80x94OR13, or a heterocyclic group;
R13, R14 mean alkyl, aryl, alkenyl or alkynyl;
R15 means H or R13;
R16 means acyl or R13;
R17 means H, alkyl, aryl or a heterocyclic group and
n means 0 or 1,
wherein at least one of the residues R11 or R12 is not H and R11 and R12, R13 and R14 or R15 and R16 may form a five- to seven-membered ring.
Particularly preferred compounds (D-I) are those in which INH denotes 
The present invention also provides a colour photographic recording material having at least one spectrally sensitised silver halide emulsion layer, characterised in that said silver halide emulsion layer contains an oil former having a pKa value of less than 18 and a DIR coupler which is of the formula
A1"Parenopenst"Time"Parenclosest"nINHxe2x80x83xe2x80x83(D-II)
wherein
A1 is of the formula 
or corresponds to the residue of a malonic acid diester, malonic acid diamide or malonic ester amide yellow coupler, of an acylacetamide or -anilide yellow coupler, of an anilino- and acylaminopyrazolone magenta coupler, of a pyrrolotriazole or pyrrolobenzimidazole magenta coupler, of a 2-acylamino-, 2,5-diacylamino- or 2-ureido-5-acylaminophenol cyano coupler or of a 2-acyl- or
2-acyl-5-acylaminonaphthol cyan coupler, which couples with the oxidation product of a silver halide developer under the conditions of photographic development and so releases the residue of the formula
"Parenopenst"Time"Parenclosest"nINH;
INH means 
Time means a linking member which, on reaction of the coupler with the oxidation product of a silver halide developer, is released together with the residue INH attached thereto and in turn releases the residue INH with a delay under development conditions;
R11, R12 mean H, alkyl, aryl, alkaryl, xe2x80x94Sxe2x80x94R13, xe2x80x94COOxe2x80x94R13, xe2x80x94CON(R13)R14, xe2x80x94N(R15)R16, xe2x80x94OR13, or a heterocyclic group;
R13, R14 mean alkyl, aryl, alkenyl or alkynyl;
R15 means H or R13;
R16 means acyl or R13;
R17 means H, alkyl, aryl or a heterocyclic group;
n means 0 or 1;
Q31 means the remaining members to complete a fused and optionally substituted benzene or heteroaromatic ring;
X31 means O or NR32;
R31 means alkyl, aryl, hetaryl or alkenyl and
R32 means H or R31, and
wherein at least one of the residues R11 or R12 is not H and R11 and R12, R13 and R14 or R15 and R16 may form a five- to seven-membered ring.
In a preferred embodiment, the compounds are of the formula (D-II), in which
R11 and R12 denote H, alkyl, aryl, xe2x80x94SR13, xe2x80x94COOxe2x80x94R13, xe2x80x94COON(R13)R14 or xe2x80x94Oxe2x80x94R13 and
R13, R14 denote alkyl, aryl or alkynyl.
Particularly preferably, the compounds are of the formula (D-II), in which INH denotes 
In another preferred embodiment, the coupler residue A1 denotes a residue of the formula (D-III) or the residue of a benzoylacetanilide yellow coupler, of an anilino- or acylaminopyrazolone magenta coupler, of a pyrrolotriazole or pyrrolobenzimidazole magenta coupler, of a 2-acylamino-, 2,5-diacylamino- or 2-ureido-5-acylaminophenol cyan coupler, or of a 2-acyl-5-acylaminonaphthol cyan coupler.
It has surprisingly been found that an increased interimage effect is also achieved with this embodiment of the photographic material according to the invention, without any reduction in sensitivity.
Examples of DIR couplers of the formulae (D-I) or (D-II), which are suitable for the material according to the invention are the compounds (D-1) to (D-23). 
In a preferred embodiment of the invention, the oil former has a pKa value of 8 to 15.
In another preferred embodiment, the oil former complies with one of the formulae (O-I), (O-II) and/or (O-III), which may also comprise polymers.
R11xe2x80x94COOHxe2x80x83xe2x80x83(O-I),
R21xe2x80x94NHxe2x80x94SO2xe2x80x94R22xe2x80x83xe2x80x83(O-II),
xe2x80x83R31xe2x80x94OHxe2x80x83xe2x80x83(O-III),
wherein
R11, R22 mean alkyl or substituted alkyl, alkenyl or substituted alkenyl, aryl or substituted aryl, heteroaryl or substituted heteroaryl,
R21 means H or R22 and
R31 means substituted aryl or substituted heteroaryl
and (O-I), (O-II) or (O-III) contain at least 8 C atoms per carboxyl, sulfonamide or phenolic hydroxy group.
In a particularly preferred embodiment, the oil former complies with one of the formulae (O-I), (O-II) and/or (O-III), wherein
R11, R22 mean alkyl or substituted alkyl, alkenyl or substituted alkenyl, phenyl or substituted phenyl,
R21 means H or R22 and
R31 means substituted phenyl.
In another particularly preferred embodiment, the oil former complies with the formula (O-I), wherein
R11 means alkyl or substituted alkyl, alkenyl or substituted alkenyl
and (O-I) contains at least 10 C atoms per carboxyl group.
For the purposes of the present invention, alkyl and alkenyl residues may be linear, branched or cyclic. Alkyl, alkenyl and aryl groups may, for example, be substituted by alkyl, aryl, heterocyclyl, hydroxy, carboxy, halogen, alkoxy, aryloxy, heterocyclyloxy, alkylthio, arylthio, heterocyclylthio, acyl, acyloxy, acylamino, cyano, nitro or mercapto groups, wherein heterocyclyl denotes a saturated, unsaturated or aromatic heterocycle and acyl denotes the residue of an aliphatic, olefinic or aromatic carboxylic, carbamic, carbonic, sulfonic, amidosulfonic, phosphoric, phosphonic, phosphorous, phosphinic or sulfinic acid.
Examples of oil formers of the formulae (O-I), (O-II) and (O-III) are listed below. 
The oil formers, couplers and DIR couplers may be produced using methods known from the literature.
Within a layer of the photographic material, the weight ratio of oil former according to the invention to DIR coupler is 1:10 to 5000:1. If the same layer contains no further coupling compounds, this ratio is 1:10 to 10:1. The application rate for the DIR coupler is 1 to 50 mg per m2 per layer of the photographic material.
In another preferred embodiment the spectrally sensitised silver halide emulsion layer contains the oil former and the magenta coupler in the form of an emulsion, wherein this emulsion may contain further additives, such as for example coupling compounds and/or other oil formers.
In another particularly preferred embodiment, the spectrally sensitised silver halide emulsion layer contains the oil former and the DIR coupler in the form of an emulsion, wherein this emulsion contains substantially no further additives.
Examples of colour photographic materials are colour negative films, colour reversal films, colour positive films, colour photographic paper, colour reversal photographic paper, colour-sensitive materials for the dye diffusion transfer process or the silver dye bleaching process. A review may be found in Research Disclosure 37038 (1995) and Research Disclosure 38957 (1996).
The photographic materials consist of a support, onto which at least one photosensitive silver halide emulsion layer is applied. Suitable supports are in particular thin films and sheets. A review of support materials and auxiliary layers applied to the front and reverse sides thereof is given in Research Disclosure 37254, part 1 (1995), page 285 and in Research Disclosure 38957, part XV (1996), page 627.
The colour photographic materials conventionally contain at least one red-sensitive, one green-sensitive and one blue-sensitive silver halide emulsion layer, optionally together with interlayers and protective layers.
Depending upon the type of photographic material, these layers may be differently arranged. This is demonstrated for the most important products:
Colour photographic films such as colour negative films and colour reversal films have on the support, in the stated sequence, 2 or 3 red-sensitive, cyan-coupling silver halide emulsion layers, 2 or 3 green-sensitive, magenta-coupling silver halide emulsion layers and 2 or 3 blue-sensitive, yellow-coupling silver halide emulsion layers. The layers of identical spectral sensitivity differ with regard to their photographic sensitivity, wherein the less sensitive sublayers are generally arranged closer to the support than the more highly sensitive sublayers.
A yellow filter layer is conventionally located between the green-sensitive and blue-sensitive layers which prevents blue light from penetrating into the underlying layers.
Possible options for different layer arrangements and the effects thereof on photographic properties are described in J. Inf. Rec. Mats., 1994. volume 22, pages 183-193 and in Research Disclosure 38957, part XI (1996), page 624.
Colour photographic paper, which is usually substantially less photosensitive than a colour photographic film, conventionally has on the support, in the stated sequence, one blue-sensitive, yellow-coupling silver halide emulsion layer, one green-sensitive, magenta-coupling silver halide emulsion layer and one red-sensitive, cyan-coupling silver halide emulsion layer; the yellow filter layer may be omitted.
The number and arrangement of the photosensitive layers may be varied in order to achieve specific results. For example, all high sensitivity layers may be grouped together in one package of layers and all low sensitivity layers may be grouped together in another package of layers in order to increase sensitivity (DE-25 30 645).
The substantial constituents of the photographic emulsion layers are binder, silver halide grains and colour couplers.
Details of suitable binders may be found in Research Disclosure 37254, part 2 (1995), page 286 and in Research Disclosure 38957, part II.A (1996), page 598.
Details of suitable silver halide emulsions, the production, ripening, stabilisation and spectral sensitisation thereof, including suitable spectral sensitisers, may be found in Research Disclosure 37254, part 3 (1995), page 286, in Research Disclosure 37038, part XV (1995), page 89 and in Research Disclosure 38957, part V.A (1996), page 603.
Photographic materials with camera sensitivity conventionally contain silver bromide-iodide emulsions, which may optionally contain small proportions of silver chloride. Photographic print materials contain either silver chloride-bromide emulsions containing up to 80 wt. % of AgBr or silver chloride-bromide emulsions containing above 95 mol % of AgCl.
Details of further colour couplers other than those according to the invention may be found in Research Disclosure 37254, part 4 (1995), page 288, in Research Disclosure 37038, part II (1995), page 80 and in Research Disclosure 38957, part X.B (1996), page 616. These compounds may occur in one or more layers of the photographic material and may also be used in a layer together with the compounds according to the invention. The maximum absorption of the dyes formed from the couplers and the developer oxidation product is preferably within the following ranges: yellow coupler 430 to 460 nm, magenta coupler 540 to 560 nm, cyan coupler 630 to 700 nm.
Details relating to further compounds other than the DIR compounds, in particular couplers, according to the invention may be found in Research Disclosure 37254, part 5 (1995), page 290, in Research Disclosure 37038, part XIV (1995), page 86 and in Research Disclosure 38957, part X.C (1996), page 618. These compounds may occur in one or more layers of the photographic material and may also be used in a layer together with the compounds according to the invention.
Colour couplers, which are usually hydrophobic, as well as other hydrophobic constituents of the layers, are conventionally dissolved or dispersed in high-boiling organic solvents. These solutions or dispersions are then emulsified into an aqueous binder solution (conventionally a gelatine solution) and, once the layers have dried, are present as fine droplets (0.05 to 0.8 xcexcm in diameter) in the layers.
Suitable high-boiling organic solvents, methods for the introduction thereof into the layers of a photographic material and further methods for introducing chemical compounds into photographic layers may be found in Research Disclosure 37254, part 6 (1995), page 292. The methods of introduction also apply to the oil formers according to the invention.
The non-photosensitive interlayers generally arranged between layers of different spectral sensitivity may contain agents which prevent an undesirable diffusion of developer oxidation products from one photosensitive layer into another photo-sensitive layer with a different spectral sensitisation.
Suitable compounds (white couplers, scavengers or DOP scavengers) may be found in Research Disclosure 37254, part 7 (1995), page 292, in Research Disclosure 37038, part III (1995), page 84 and in Research Disclosure 38957, part X.D (1996), pages 621 et seq..
The photographic material may also contain UV light absorbing compounds, optical brighteners, spacers, filter dyes, formalin scavengers, light stabilisers, antioxidants, Dmin dyes, plasticisers (latices), biocides and additives to improve coupler and dye stability, to reduce colour fogging and to reduce yellowing, and others. Suitable compounds may be found in Research Disclosure 37254, part 8 (1995), page 292, in Research Disclosure 37038, parts IV, V, VI, VII, X, XI and XIII (1995), pages 84 et seq. and in Research Disclosure 38957, parts VI, VIII, IX and X (1996), pages 607 and 610 et seq..
The layers of colour photographic materials are conventionally hardened, i.e. the binder used, preferably gelatine, is crosslinked by appropriate chemical methods.
Suitable hardener substances may be found in Research Disclosure 37254, part 9 (1995), page 294, in Research Disclosure 37038, part XII (1995), page 86 and in Research Disclosure 38957, part II.B (1996), page 599.
Once exposed with an image, colour photographic materials are processed using different processes depending upon their nature. Details relating to processing methods and the necessary chemicals are disclosed in Research Disclosure 37254, part 10 (1995), page 294, in Research Disclosure 37038, parts XVI to XXIII (1995), pages 95 et seq. and in Research Disclosure 38957, parts XVIII, XIX; and XX (1996), paces 630 et seq. together with example materials.